Re: Help in remembering commutative etc needed, at kindergarten level!

hi Margarita,

Haven't got a 'mnemonic' as such but this is what I do:

Commutativity:

A x B = B x A etc

At rush hour people from town A get in their cars and drive to work in town B. And people in town B get in their cars and drive to work in town A. At the end of the day, they all swap back. I believe that's why they are called commuters; because they swap over.

Associativity:

If you've got three numbers to multiply / add / divide etc, which ones do you associate together first?

A # B # C ?

Is it A # B, get the answer and then do (answer # C)

Or is it B # C, get the answer and then do (A # answer).

So it's all to do with the ones you associate together first.

# is an associative operation if

(A # B) # C = A # (B # C)

Distributivy:

A # (B @ C) where # and @ are different operations you can do with 2 numbers.

So A has to be distributed to the contents of the bracket; B gets it and C gets it:

(A # B) @ ( A # C)

You are probably learning which operations are commutative, associative and distributive over another operation.

What is correct in each case is much more important than remembering the correct word, so I shouldn't worry too much about them.

Hope that helps,

Bob

Last edited by bob bundy (2013-02-13 00:29:09)

Children are not defined by school ...........The FonzYou cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Re: Help in remembering commutative etc needed, at kindergarten level!

Thank you again, Bob. Yes, the ideas are easier than the names!I was doing the exercises at the mathopolis link where they ask you to click on which law was in operation for a given equation. I knew what the equations were doing but I kept getting the name wrong!